Method and apparatus for separating materials



Sept. 27, 1960 w. A. COLBURN METHOD AND APPARATUS FOR SEPARATINGMATERIALS Filed June 17, 1957 2 Sheets-Sheet 1 FEED CONCENTRATE I3 15ZERH CLEANER $-I4 NON MAGNETIC MATERIALS FXER bJ|AGNET |ZER H s PARATORHDEMAGNETI William A. Colburn BY ATTORNEYS Sept. 27, 1960 A, OLB N2,954,122

METHOD AND APPARATUS FOR SEPARATING MATERIALS Filed June 17, 1957 I v 2Sheets-$heet 2 I II OI William A. Colburn ATTORNEYS METHOD AND APPARATUSFOR SEPARATING MATERIALS William A. Colhurn, Denver, Colo., assignor toPetroleum Research Corporation, Denver, Colo., a corporation of ColoradoFiled June 17, 1957, Ser. No. 665,903

6 Claims. (Cl. 209-8) 'netic material. Magnetic separators are employedwidely in the mining industry, some being adapted for use in dry,pulverized ore and others in wet, ground ore or slurry. In general,these separators will separate moremagnetic material from less-magneticmaterial; however, when the more magnetic material is only weaklymagnetic or when the material is very finely divided, the force exertedby the magnetic field of the separator often is not t ti States Patent rsufficient to remove the more magnetic material effectively. Thisdimculty arises because the magnetic forces are not sufficiently strongto force the more magnetic material through the mass of material so thatthe particles of 'rnagnetic material can reach the magnetic pole orcollector;

is further increased because the more magnetic material must be drawnthrough the mass of material in directions transverse to the directionof flow or movement of the mass of material. The conventional magneticseparators and, in most types of commercialseparators, this diflicultyI,

are highly eflective for separating ferro-magnetic material fromnon-magnetic material; however, they are not entirely satisfactory forseparating and collecting weak magnetic materials. By way of example,-the present com mercial separators are relatively ineflicient whenemployed to separate weakly magnetic tungsten ores such as W01-frlann'te from the rock in which they occur. Accordingly,

it is an object of the present invention to provide an improved methodfor separating weakly magnetic materials from non-magnetic materials.

It is another object of this invention to provide an int-- providemethod for treating a mass of finely-divided materials to separate themore-magnetic material from the fless-magnetic material in the mass.

1 It is a further object of this invention to provide an improvedapparatus for separating more-magnetic material from less-magneticmaterial.

Briefly, in carrying out the process of this invention "in one formthereof, a mass of material to be treated, for example arelatively-thick slurry formed from finelydivided tungsten ore, isthoroughly mixed with a-multi- -pliicity of relatively large bodies ofhighly-magnetizable material such as balls or shotlike bodies of alnico.The mixture'is then passed through amagnet-ic field to magnetize thealnico bodies and is then passed to a conventional magnetic separator toremove the alnico bodies from the moving'mass of the ore. 'When the massof material is treated in this way, the magnetic bodies pick upfinely-divided weakly-magnetic material within the mass andcarry it withthem through the magnetic separation :process so that the magneticbodies are'removed with finely-divided weakly-magnetic matenialadhering,to them.

2,954,122 Patented Sept. 1960 The weakly-magnetic material which is tobe recovered is then cleaned fromthe magnetic bodies, preferably bytie-magnetizing the bodies and washing them over a screen so that thefinely-divided ore and the bodies are thereby separated. The bodies arethen returned to move again through the process. This method maysimilarly be applied to dry, pulverized ore and, in some applications,the separation may be accomplished by a mechanical ap-v paratus insteadof by a magnetic separator. In another form, magnetic bodies secured toa moving belt may be employed instead of the free bodies. The apparatusemployed in practicing the invention in one embodiment thereof comprisesa mixing hopper and an agitator for thoroughly distributing themagnetizable bodies through? out the mass of finely-divided ore. Aconveyer then care ries the mixture through a magnetizing field formagnetizing the highly-magnetizable bodies. The mixture is thendischarged and delivered to a magnetic separator which separates themagnetizable bodies from the mixture and discharges them through ade-magnetizing field. A wash.- ing and screening apparatus is thenarranged to receive the de-magnetized bodies and to clean them andremove the adhering pulverized material which is collected while themagnetizable bodies are returned to the beginning of the circuit.

The features of novelty which characterize this invention will bepointed outwith particularity in the appended claims' The inventionitself, however, both as to the method for treating finely-dividedmaterial and as t9 the organization and arrangement of the apparatusembodying the invention, together with further objects and advantagesthereof, will be better understood upon refer.- .ence to the followingdescription taken in connection the accompanying drawings in which:

Fig. 1 is a block diagram or flow sheet illustrating the process of theinvention; a

Fig. 2 is a diagrammatic illustration of a wet process apparatus forseparating materials in accordance with the inv ntion;

' Fig. 3 is a diagrammatic illustration similar to Fig. 2 showing adry-type apparatus for separating materials in accordance with theinvention;

Fig. 4 is a plan view of the apparatus diagrammatically sh w i ig- Fig.5is a diagrammatic illustration of a dry process apparatus includinganother embodiment of the invention Pig. 6 is 'a diagrammaticillustration of a further embodirnent of the invention;

Fig. 7 is a diagrammatic illustration of a still further embodiment .ofthe invention; and

Figs. 8 and 9 illustrate modified forms of magnetic belts for use inapparatus of the type shown in Figs. 6 and 7 Referring-now to thedrawing, the several steps in the process of the present invention areindicated in thc block diagram in Fig. 1. In carrying out the process, afinely-divided ore or other material containing moremagnetic andless-magnetic materials, from which it is desired to remove the moremagnetic material as a concentrate, is supplied to a mixing apparatusindicated at '10. The feed may be either wet or dry depending on thematerials to be handled and the apparatus available.

netizab le material; this material, for example, maybe ,a

quantity of shotor spheres of highly-magnetizable mate- .rial such asalnico. The magnetizable bodies and thc .feed are thoroughly mixed inthe mixer 10 and are then supplied to a magnetizer 1 1 which magnetizesthe larger "bodies and also other magnetizable particles in the mix. Thecomplete mixture is .then supplied to a n'agrieticgr niechaniealsepartor .12 which removes the large bodies togetherwith any smallparticles of magnetic material 3 adhering thereto and supplies them to ademagnetizer 13 while the non-magnetic material is discharged through anoutlet indicated at 14. From the de-magnetizer 13 the bodies andadhering ground material are supplied to a cleaner 15 which removes theadhering material and discharges it through a concentrate outlet 16while returning the bodies of magnetizable material through a returnpath indicated at E7. The effectiveness of this process depends upon theaction of the magnetizable bodies when they are magnetized within themass of material. The thorough mixing of the bodies in the mass ofmaterial assures the presence of magnetic poles throughout the materialwhen the mixture passes through the magnetizer it. Thus the magneticpoles are provided colse to the magnetic particles within the materialand the particles are not required to pass through substantial portionsof the body of ground material in order to reach a magnetic pole. Thesmall particles cling to the surfaces of the magnetic bodies and arecarried to the magnetic separator where the bodies are removed from thenonmagnetic pulverized material and carry with them the magneticmaterial which is held on the surfaces of the bodies by magnetic force.The magnetized bodies have been represented in the drawing as havingirregular surface outlines due to the particles atracted thereto. Theseparator 12 is preferably a magnetic separator which readily removesthe larger bodies of magnetized material; however, other forms ofseparators may be employed which will remove the larger bodies from thepulverized mass; for example, a trommel may be employed to screen outthe finer non-magnetic material and to deliver the magnetized bodies andadhering material to the demagnetizer 13. After the magnetic bodies havebeen demagnetized, they are passed to the cleaner which may be of anysuitable type; for example, a screen and washing spray may be employedwhen the process is a wet process and a blower and dust collector may beemployed in the dry process. The return circuit 17 for the magnetizablebodies may be of any suitable construction; for example, it may be acontinuous belt or a chain and bucket device. Regardless of theapparatus employed, the essential feature of the process of thisinvention is the and then discharged through a connection 20a to arotary pump 26 which forces the mixture to flow through a conduit 27 andthence to a tank or trough 28 of a belt-type magnetic separator fit).The pump 26 serves to propel the mixture and also to mix themagnetizable bodies or shot more thoroughly and more uniformlythroughout the finely-divided ore mass. In order to magnetize the shot24 as the mixture passes through the conduit 27, a directcurrentmagnetizing coil 32 is arranged about the conduit and is energized by asuitable directcurrent source indicated diagrammatically as a battery33. The coil 32 produces a magnetic field extending along the axis ofthe conduit 27 and the magnetic bodiespassing therethrough are thusmagnetized. The magnetized bodies tend to collect in strings, and,furthermore, magnetic material contained in the finely-divided materialmixture is also magnetized and collects on the shot; furthermore, as theshot moves together through the mixture, it passes in close proximity tothe slightly magnetic particles in the mixture and they readily adhereto the shot and travel along with it. In this manner, strong magneticpoles are provided throughout the mixture so that none of the materialhas to travel a great distance through the moving mixture in order toreach a magnetic pole and even weakly-magnetic material is collectedfrom the mixture of material flowing through the conduit. The materialthen flows through the magnetic separator 30 below a belt 34 mounted formovement about two drums or wheels 35 and 36 and driven in the directionof movement of the material toward an outlet weir 37. As the materialpasses the central area of the belt, between the two drums, it comeswithin the field of a series of magnets indicated generally at 38, andthe relatively large bodies of highly-magnetized material are drawnagainst the belt by the, magnets and are carried along until the beltreaches the end of the magnets 38 whereupon the magnetic bodies arereleased and fall into a funnel or catching bin,

. the non-magnetic materials and the liquid continuing distribution ofmagnetic poles throughout the mass of material to be treated so thatnone of the material is required to travel any substantial distance inorder to reach a magnetic pole and to be separated from the othermaterial. This method has been found eifective for removing relativelyweak magnetic materials from a mass of nonmagnetic material and, forvexample, has been found suitable for removing tungsten ore such aswolframite from the rock in which it occurs. In some applications, themagnetic field of the separator will be sufiicient for magnetizing thebodies and the separate magnetizing coil is unnecessary; also, forseparating some materials it may be found unnecessary to employ thedemagnetizing coil before passing the magnetic bodies to the cleaningapparatus.

Many different types of apparatus for performing the functions of thecomponents of the system indicated in Fig. 1 may be employed for thecarrying out of the process of this invention. By way of example, inFig. 2 there is illustrated a system employing a wet process andarranged to separate more magnetic material from less magnetic materialcontained in a pulp or slurry of ore. A system of this type may beemployed, for example, to separate wolframite or tungsten ore from thetailings flowing from a molybdenum ore mill. In the system of Fig. 2, amixing chamber or hopper 20 is supplied with a pulp or slurry through aninlet duct 21 and the pulp within the tank 20 is agitated by an impeller22 driven by suitable mechanism (not shown) through a shaft 23. Highlymagnetizable material, preferably in the form of small spheres or shot24 and which may be 'alnico, is supplied to the tank 20 through aconduit or supply chute 25 and the shot and slurry in the tank 20 arethoroughly mixed through the tank and out over the weir 37. As thebodies 24 fall downwardly from the funnel 40, they pass through a duct41 and are de-magnetized by operation of an alternating magnetic fieldproduced by a coil 42 connected to a source of alternating current 43.The de-magnetized bodies fall onto a suitable cleaning apparatus whichhas ben shown as a screen 44 and are cleaned by suitable mechanism whichmay be a spray head 45 arranged to spray the de-magnetized bodies withwater and wash the finely-divided material adhering thereto through thescreen and into a collecting funnel 47 from which it may be removedthrough a duct 48. The magnetized bodies 24 fall from the screen into acollecting funnel 50 and thence through a duct 51 to a return mechanismindicated diagrammatically as a bucket chain 52 so that the bodies 24are returned through the supply duct 25 to the tank 20.

The operation of the system shown in Fig. 2 is continuous and makes itpossible to remove relatively-weak magnetic materials such as wolframitefrom non-magnetic material such as the rock in which tungsten oresoccur. The process of this invention, by bringing strong magneticpolesinto close relationship with the finely-divided material throughoutthe mass of material, makes it possible to remove small particles ofmagnetic material and weakly-magnetic material from a mass of movingmate rial although such particles would not be effectively removed bythe action of conventional magnetic separators.

The apparatus illustrated in Figs. 3 and 4 is similar to thatillustrated in Fig. 2 but is of the type which may be employed foroperation on dry materials or powder. In the apparatus of Figs. 3 and 4,the process of the invention is carried out by supplying dry pulverizedmaterial to be treated and relatively-large highly-magnetizable bodiesto a hopper 5 4 which feeds a mixer 55 from which tween 5 7 and 58. Thesupply of mixed material, indicated at 59, moves along with the beltthrough a. nonmagnetic cylinder 61 about which is arranged a magnetizingcoil 62 supplied with direct current from a suitable source 62a. Thus,as the material on the belt 56 passes through the cylinder-61, thehighly-magnetizable bodies are magnetized to provide strong magneticpoles throughout the mixture, thereby attracting particles ofweaklyinagnetic material to the bodies Within the mass 59. The material59 then passes through a magnetic separator indicated generally at 63and comprising suitable magneticpole pieces 64 and 65 arrangedon theupper and lower sides of the belt 56 to provide a magnetic fieldextending through the material 59. The separator 6'3 may also beprovided with a stirrer or agitator (not shown) to release non-magneticmaterial held mechanically to the magnetic material moving to the belt.The magnetized bodies are drawnthrough the mass of material 59 towardthe pole 64 and are caught on the bottom side of the lower pass of across belt 66 by which they are moved transversely of the path of thebelt 56 and carried through a tie-magnetizing coil 67 supplied withalternating current from a suitable source 68; thus, the magnetizedbodies in the material are demaguetized and then fall from the belt 66at the upper end as viewed in Fig. 4 and may be collected-in a suitablehopper 70. The particles adhering to the bodies of magnetic material maythen be removed by a suitable cleaner (not shown) and the magnetizablebodies-returned'to the hopper 54. The non magnetic materialiscarried tothe end of the belt 56 and hails from the belt asit passes over the drum58 and may then be transported in any suitable-manner to the Waste ortailings dump. 7

As illustrated in Fig. 5, it may be desirable in some applications toemploy a mechanical separator other than a magnetic separ'tor forremoving the bodies of magnetizable material from the-mass of pulverizedmaterial. The apparatus of Fig. 5 is essentially similar to that ofFigs. 3 and 4 and corresponding parts have been designated by the samenumerals with the addition of the suflix a. Instead of passing to themagnetic separator 63 of Figs. 3 and 4, the belt 56a delivers themixture of pulverized material and magnetized bodies to a trome mel orrotating screen 71 which screens the non-magnetic material from themagnetized bodies and the more-magnetic material adhering thereto. Themagnetized bodies and the material which they carry then pass through aconduit 72 into a hopper 73. A de-rnagnetizing coil 74 is provided aboutthe conduit 72 and the magnetized bodies are thereby de-magnetizedbefore being supplied to the hopper where the adhering material iscleaned therefrom before the bodies are returned to the beginning of thecircuit. The concentrate comprising the moremagnetic materials securedby cleaning the magnetic bodies is then collected and delivered for useor shipment.

Instead of employing free magnetizable bodies such as the shot or ballsused in the apparatus illustrated in Figs. 2 through 5, the magnetizablemembers may be secured to a suitable anchoring means such as a belt orchain so that they can be moved along with or drawn through thefinely-divided material to be treated. By way of example, there isillustrated in Fig. 6 a portion of a dry-type apparatus similar to thatof Figs. 3 and 4 and which is provided With a belt carrier for themagnetizable bodies. The parts of the apparatus corresponding to partsof the apparatus of Figs. 3 and 4 have been designated by the samenumerals with the suffix letter b. In this modification, a continuous,flexible belt 75 is mounted to move over drums 76 and 77 and has securedto it a multiplicity of magnetic spikes or bars 78 extendinglongitudinally of thebelt and parallel to its surface and secured to thebelt on suitable posts 79. The magnetizable elements 78 which may bemade of alnico or other highlymagnetizable material are arranged instaggered relationship so that, as the belt which is mounted parallel tothe belt 56b passes adjacent the belt 56b, the magnetizable members willlie at'various depths within the mass of material to be treated,indicated at 59b. Both belts pass through a field produced by a coil 62band the elements 78 are thereby magnetized and collect particles. ofmore-magnetic material from the mass of material 59b through which themagnetizable elements are passing. The belt75 extends beyond the drum58b for the belt 56b and then passes through a demagnetizing fieldproduced by a coil 67b surrounding the belt and energized from asuitable source of alternating current 68b. Pa;rticles falling from themagnetizable elements 78 after they have been ale-magnetized drop to ahopper 70b and any particles still adhering to the elements 78 areblown'therefrom by an air blast indicated generally at 80 as the beltturns upwardlyover the drum 77.

' In Fig. 7,there is shown an apparatus wherein a belt similar to thebelt 75 of Fig. 6 is employed as the main transporting belt of thesystem. 'In this system, a belt is arrangedto move over drums 86 and 87a d material to be treated is supplied to the belt from a suitablehopper 88 and mixer 89 supplied with a mixture of the finely-dividedmaterial-to be treated. The belt is constructed in essentially the samemanner as the belt 75 of Fig. 6 so that the material supplied to thebelt is distributed about a plurality of short magnetic elements or bars90 extendinglongitudinally of the belt' in stag gere'd positions overthesurface ofthe belt and spaced therefrom. Material then passes through amagnetizing coil 91 which magnetizes the bars 90 and causes them to pickup finely-divided rnore-magnetic material from the material on the belt,then as the material falls from the belt when it turns over the drum 87,the magnetic bars 90 carry thecollected material downonto the undersideof the belt" which then passes through a de magnetizing field producedby a coil 93 energized by a suitable source of alternating current 94.When the bars 90 are thus de-magnetized, the particles adhering theretofall and any which do not fall ime may be cleaned from the bars by anair blast indicated at 95. The finely-divided material thus removed maybe collected in any suitable manner such as by a vacuum machine having acollecting filter bag as indicated at 97.

Other for-ms of belts carrying magnetic elements and suitable for use inapplications such as those of Figs. 6 and 7 are shown in Figs. 8 and 9.The belt shown in Fig. 8 comprises a series of longitudinal non-magneticwires 98 woven together with a plurality of short magnetic wires 99,thereby forming a grid having magnetic pole members extending across thelongitudinal wires. When a belt of this type is magnetized by a fieldhaving its lines of force extending parallel to the Wires 98, the Wires99 are magnetized oppositely on their front and trailing edges. Thearrangement shown in Fig. 9 is similar to that of Fig. 8 except that themagnetizable wires, indicated at 100, are provided with additionalelements or barbs 101 in a manner similar to that employed in makingbarbed wire, thereby distributing the magnetic-poles more completelythroughout the mass of material to be treated.

While the invention has been illustrated and described in connectionwith particular applications, other applications and arrangements ofapparatus will occur to those skilled in the art. Therefore, it is notdesired that the invention be limited to the specific embodiments andmethods illustrated and described and it is intended by the appendedclaims to cover all modifications which fall Within the spirit and scopeof the invention.

I claim:

1. In the materials separating art, the method of separating particlesof more magnetic material from a mass comprising particles of moremagnetic material and particles of less magnetic material whichcomprises mixing in the mass relatively large bodies of highlymagnetizable material of high retentivity, passing the bodies through amagnetic field to magnetize them,'said bodies retaining their magnetismafter passing from the magnetic field, separating the bodies andparticles magnetically held thereon from the remainder of the mass, andcleaning the bodies to remove and collect the particles of materialtherefrom.

2. In the materials separating art, the method of separating particlesof more magnetic material from a mass comprising particles of moremagnetic material and particles of less magnetic material, whichcomprises mixing in the mass relatively large tree bodies of highlymagnetizable material, moving the mass of material with the magnetizablebodies therein into a transversely acting magnetic field to magnetizethe bodies, passing the mass through a magnetic separator to separatethe bodies with particles of more magnetic material thereon from theremainder of the mass, demagnetizing the bodies, cleaning the bodies toremove the particles of material therefrom, and collecting the removedmaterial.

3. The method of separating more magnetic materials from less magneticmaterials which comprises mixing a mass of finely-divided material to betreated and a quantity' of substantially larger free bodies of readilymagnetizable material to distribute the bodies throughout the mass offinely-divided material, subjecting the mixed mass to a magnetic feld tomagnetize the bodies, separating the bodies and finely-divided materialclinging thereto from the remainder of the mass, demagnetizing thebodies, and cleaning the bodies to remove the finely divided materialtherefrom.

4. In the magnetic material separating art wherein a magnetic separatoris employed to remove more magnetic particles from a mass of lessmagnetic particles, the method of facilitating the removal of the moremagnetic particles which comprises mixing free bodies of readilymagnetizable' material in the mass of particles tobe treated andmagnetizing the bodies prior to supplying the mass of material to themagnetic separator whereby the bodies with more magnetic particlesclinging thereto are removed from the mass by the separator, andthereafter cleaning the bodies to removethe particles of materialtherefrom;

5. The method for facilitating the removal of more magnetic materialfrom less magnetic materials as recited in claim 4 including the furtherstep of demagnetizing the separated bodies prior to cleaning them toremove particles therefrom. 6. In the materials separating art, .themethod of separating particles of more magnetic material from a masscomprising particles of more magnetic material and particles of lessmagnetic material which comprises distributing in the mass at aplurality of 'difierent depths therein relatively large bodies of highlymagnetizable material of high retentivity, subjecting the bodies to amagnetic field to magnetize them while in said mass, said bodiesretaining their magnetism after removal of the magnetic field,separating the bodies and particles magnetically held therein from theremainder of the mass, and cleaning the bodies to remove and collectparticles of material therefrom.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Dec. 7,

